The present invention relates to an apparatus and method for repairing pipe, such as underground sewer pipe and the like.
Prior methods for repairing damaged sections of pipe include moving a liner tube impregnated with a resinous material capable of curing and hardening to a position within the pipe where the damaged portion is located. Once the liner tube is positioned within the host pipe, it is pressurized, causing the liner to press against the interior wall of the host pipe, and the liner is cured by applying heat, such as with steam or hot water. These liners can also be cured at ambient temperatures by a chemical mixture which generates an exothermic reaction or by ultraviolet light. The liner tube forms an interior liner in the pipe for the pipeline being repaired. Such a process is commonly known as cured-in-place pipelining.
The liner tube is positioned within the pipe by pulling, pushing or inverting the liner. Pulling or pushing a liner into position within a pipe can be an efficient process, particularly in situations where the liner must only travel a short distance and need not navigate significant bends in the pipe. Typically, a flat sheet liner is wrapped around an inflation plug to form a tube with the longitudinal edges of the sheet overlapping. The inflation plug with liner is then pushed or pulled into position adjacent the damaged section of pipe.
Although a pull-in-place or push-in-place installation is feasible in many instances, problems remain. For example, prior art lining tubes are typically made of a fabric material that is resin absorbent. Once the resin is applied to the liner, there is nothing around the outside of the liner to contain the resin. Consequently, resin is wiped off of the liner when the liner rubs against the interior of the host pipe as the liner is either pulled or pushed into position. Workers must also take great care so as to not come into contact with the resin and also avoid contaminating the exposed resin impregnated liner.
Prior art liners pushed or pulled in place are also not well suited for lining at bends in the pipeline. Flat sheet liners with overlapping edges are not capable of stretching or expanding sufficiently to avoid folds in the liner when pressed against the interior of the host pipe. In addition, flat sheet style liners must be banded, strapped, tied or otherwise attached with fasteners to the inflation plug to avoid falling off the plug prior to inflating the plug and pressing the liner against the interior of the host pipe.
Additionally, there are deficiencies in the art of liners for inversion systems. U.S. Pat. No. 5,927,341 to Taylor teaches impregnating a liner with a resinous material by thoroughly saturating the liner tube. At one end of the liner tube, a collar or flat sheet may be attached, to act as a brim within the main pipe. The lateral tube and the collar or flat sheet is placed onto a bladder device, where a lateral bladder is already inverted inside the bladder device. The lateral bladder is then everted into the lateral liner tube. The lateral bladder is then reinverted within the bladder device, along with the lateral liner. The loaded bladder device is then aligned with the junction to be repaired, and the lateral bladder is everted a second time, placing the lateral liner against the interior of the lateral pipe. This will be referred to as a “two-step inversion process.”
There is an advantage to using a two-step inversion process. The fact that an inflatable bladder may be used multiple times provides the greatest advantage. Since the liner is simply placed on top of the bladder device, the bladders may be easily reused, as long as durable materials are used. However, as presently used in the art, there are several disadvantages to using a two-step inversion process. First, if a coating is present on the lateral liner, the coating will be pressed against the interior of the pipe wall when using this two-step inversion process. The coating side of the lateral liner will be pressed against the interior walls of the host pipe because the coating acts to contain the resinous material during the impregnation process. Pressing a coating against the interior walls of a host pipe may be problematic because in order to seal a lateral pipe, resin migration into the fractures and the open joints of the host pipe is required. This resin migration prevents water infiltration/exfiltration and to prevent roots from entering the system. Additionally, ASTM F-1216 requires resin migration to the lateral pipe, which is the specification that engineers use to determine the quality of a pipe sealing product.
These problems have been addressed previously in the art. For example, U.S. Pat. No. 6,039,079 to Kiest discloses a method of lining a pipe where a lateral liner tube is impregnated with a resinous material after being placed into a launcher device. This addresses the problem of needing a coated liner, because the inflatable bladder acts to contain the resin within the liner. While this allows the coating of the liner to be on the inside of the cured-in-place pipe, encouraging resin migration into the host pipe structures, the bladder is generally not available for reuse because it may be damaged or stretched during the impregnation or installation processes.
In light of the foregoing, the primary objective of the present invention is to provide an improved method and apparatus for lining pipe.
Another objective of the present invention is to provide a new resin absorbent liner that contains the resin in the liner prior to stretching the liner and pressing it against the interior of the host pipe.
Another objective of the present invention is to provide a new lining apparatus for pull-in-place or push-in-place applications that prevents resin from being wiped off of the liner as it is moved into the pipe, yet allows the resin to contact the interior of the host pipe once the liner is expanded or stretched under pressure.
Another objective of the present invention is to provide a new lining apparatus and method for effectively lining at bends and turns in the pipeline.
Another objective of the present invention is to provide a new lining apparatus and method for inversion applications, where resinous material is permitted to migrate through an outer coating of a liner into the cracks and fissures of the interior of a host pipe.
Another objective of the present invention is to provide a new lining apparatus and method for use with inversion applications, where a single-piece main and lateral bladder is used for renewing the junction of a sewer main/lateral connection multiple times.
A still further objective of the present invention is to provide a new lining apparatus which is economical to manufacture, durable in use and efficient in operation.